Hydraulic nuts are well known and have been in wide use throughout the industry for many decades.
More recently, hydraulic nuts are made up of an inner body that is threaded on to the stud to be tightened, an outer body that acts as a piston to generate an axial load to clamp the work pieces being joined and a locking collar to mechanically maintain the axial load generated by the hydraulic pressure in the annual piston created between the inner and outer bodies. The gap between the inner and outer bodies needs to be sealed so that hydraulic pressure is generated. This is achieved by a built-in or added sealing device.
Assembly of thousands of bolted flanged connections occurs annually throughout the resource processing industries of oil and gas, power generation and other manufacturing industries. General assembly technologies primarily include hand or hammer tightening and some torque tightening. Problems remain with these general tightening processes that result in failure of the clamped connection, delays and work place injuries.
Hydraulic nuts have been seen to address these concerns. However, present forms of hydraulic nuts limits their use on a variety of applications.
Some of the limitations of present hydraulic nut technology concern the space envelope required to fit the nut, reliable assembly and disassembly of the nut after repeated operating cycles at high temperature, inability to sustain high pressures, the speed needed to install the nuts and the loss of load from the locking collar.
The aim of this invention is to broaden the use of hydraulic nut technology so that a wider number of applications can realize its benefits. There is therefore a need for a hydraulic nut which can obviate the above-mentioned limitations.